WO2011129317A1

WO2011129317A1 - Cryogenic refrigerator

Info

Publication number: WO2011129317A1
Application number: PCT/JP2011/059052
Authority: WO
Inventors: 貴裕松原
Original assignee: 住友重機械工業株式会社
Priority date: 2010-04-14
Filing date: 2011-04-12
Publication date: 2011-10-20
Also published as: KR101440709B1; CN102844633A; US8899053B2; JP5575880B2; KR20130009840A; JPWO2011129317A1; US20130031916A1; CN102844633B

Abstract

Disclosed is a cryogenic refrigerator having a cylinder to which refrigerant gas is supplied, a displacer which reciprocates within the cylinder, a drive device which reciprocates the displacer within the cylinder, and a coupling mechanism for coupling the drive device to the displacer. The coupling mechanism has an output shaft extending from the drive device toward the displacer, an engagement pin which penetrates the output shaft so as to extend in a direction intersecting with the reciprocating direction of the displacer, a rotation prevention mechanism which engages with the engagement pin when the displacer rotates, to prevent the displacer from rotating, and a closure which is secured to one end of the displacer and engaged with the output shaft.

Description

Cryogenic refrigerator

The present invention relates to a cryogenic refrigerator, and more particularly, to a cryogenic refrigerator having a connecting mechanism for connecting a driving device and a displacer.

Generally, Gifford McMahon refrigerator (hereinafter referred to as GM refrigerator) is known as a refrigerator that generates cryogenic temperatures. This GM refrigerator is a refrigerator that obtains a cooling effect on the basis of the Gifford-McMahon cycle in which the movement of a displacer containing a regenerator and the adiabatic expansion of refrigerant gas by a valve are linked.

GM refrigerator first supplies refrigerant gas whose pressure is increased by a compressor to a cylinder. At this point, the displacer is at bottom dead center. The displacer is raised by the pressure difference of the refrigerant gas and by the power of the motor. When the displacer reaches the top dead center, the valve is switched, the refrigerant gas accumulated in the lower part of the displacer is adiabatically expanded, the refrigerant gas is cooled, and heat is exchanged with the regenerator material built in the displacer. At that time, the displacer begins to descend, and when it returns to the bottom dead center, the valve is switched, and the refrigerant gas whose pressure has been increased again by the compressor enters the cylinder and is cooled by exchanging heat with the regenerator material in the displacer, and this is repeated. Thus, the heat load flange portion at the lower end of the cylinder is cooled. Generally, the reciprocating motion of the displacer is obtained by converting the rotational motion of the motor into a linear motion using a crank mechanism or a scotch yoke mechanism (see, for example, Patent Document 1).

Conventionally, when the output shaft of the scotch yoke mechanism that reciprocates is connected to the displacer, the coupling mechanism shown in FIGS. 7 and 8 has been used. This coupling mechanism is composed of a pin collar 102, a parallel pin 104, an upper cup 105, a spring pin 107, and the like.

The output shaft 101 is a rod-shaped member and reciprocates in the vertical direction in the figure when connected to a scotch yoke (not shown). A donut-shaped pin collar 102 is fitted to the lower end portion of the output shaft 101, and is fixed by parallel pins 104 that pass through the pin collar 102 and the output shaft 101.

A shaft hole 103a is formed in the upper end surface of the displacer 103, and an output shaft 101 and a pin collar 102 are inserted therein. An upper cup 105 is fixed to the upper end surface of the displacer 103 by a fixing bolt 106.

An opening 105a is formed at the center of the upper cup 105, and the output shaft 101 extends upward through the opening 105a. The diameter of the pin collar 102 is set larger than the diameter of the opening 105a.

In the above configuration, when the output shaft 101 moves upward, the upper surface of the pin collar 102 engages and is pulled by the upper cup 105, whereby the displacer 103 moves upward in the cylinder 100. On the other hand, when the output shaft 101 moves downward in the figure, the displacer 103 is pressed downward by the pin collar 102, and thus the displacer 103 moves downward in the cylinder 100. As a result, the displacer 103 reciprocates within the cylinder 100.

Further, since the GM refrigerator generates cold by expanding the refrigerant gas in the cylinder 100, when the refrigerant gas flows between the inner wall of the cylinder 100 and the outer wall of the displacer 103 (so-called refrigerant gas blow-off occurs). ), Which causes a decrease in cooling efficiency. Therefore, a seal material 108 that is in sliding contact with the cylinder 100 is provided on the side surface of the displacer 103 to suppress the occurrence of refrigerant gas blow-through.

By the way, when the displacer 103 reciprocates in the cylinder 100, if the displacer 103 rotates around the axis of vertical movement, the seal material 108 disposed on the side surface of the displacer 103 and the inner peripheral surface of the cylinder 100 will hit. The surface will change. For this reason, blow-by of the refrigerant gas occurs, and the cooling process by the GM refrigerator becomes unstable. In order to prevent this, a mechanism (rotation prevention mechanism) for preventing the displacer 103 from rotating is added to the above-described coupling mechanism.

As shown in FIG. 8 in addition to FIG. 7, the conventional rotation prevention mechanism press-fits and fixes the spring pin 107 to the upper cup 105 and forms the groove 102a in the pin collar 102, and engages the spring pin 107 with the groove 102a. It was supposed to be configured. The output shaft 101 is restricted from rotating by being connected to a scotch yoke or the like. Further, the displacer 103 is restricted from rotating with respect to the output shaft 101 by a spring pin 107. Thus, the conventional rotation prevention mechanism is configured to prevent the displacer 103 from rotating in the cylinder 100.

JP 2007-205582 A

However, in the conventional cryogenic refrigerator described above, the upper cup 105 is press-fitted and fixed to the upper cup 105, and the spring pin 107 that has been press-fitted is engaged with the groove 102a formed in the pin collar 102, thereby preventing rotation. When a force to rotate the displacer 103 is applied, all the force is applied to the spring pin 107.

For this reason, the conventional cryogenic refrigerator has a problem that the spring pin 107 may be broken. If the spring pin 107 is broken, the displacer 103 rotates in the cylinder 100, and the freezing process by the cryogenic refrigerator becomes unstable.

The present invention has a general object to provide an improved and useful cryogenic refrigerator that solves the problems of the prior art described above.

A more detailed object of the present invention is to provide a cryogenic refrigerator that stabilizes the freezing process by preventing the displacer from rotating.

To achieve this object, the present invention provides a cylinder to which a refrigerant gas is supplied,
A cryogenic refrigerator having a displacer that reciprocates in the cylinder, a drive device that reciprocates the displacer in the cylinder, and a connecting mechanism that connects the drive device and the displacer;
The coupling mechanism includes an output shaft extending from the driving device toward the displacer, an engagement pin provided through the output shaft so as to extend in a direction intersecting a reciprocating direction of the displacer, A rotation preventing mechanism that engages with the engaging pin when the displacer rotates to prevent the displacer from rotating; and a lid that is fixed to the one end of the displacer and engages with the output shaft. It is characterized by.

Further, in the above invention, the rotation preventing mechanism includes a pair of engaging grooves that are formed in the displacer and that engage with both end portions of the engaging pin when the output shaft is attached to the displacer. It is good also as a structure.

Further, in the above invention, the rotation preventing mechanism has a standing pin that is erected on the displacer and that engages both end portions of the engaging pin when the output shaft is mounted on the displacer. Also good.

In the above invention, the engagement pin may be a solid round bar.

In the above invention, the standing pin may be a bolt, and a screw portion formed at a lower portion may be screwed into the displacer, and an upper portion may be engaged with a concave portion formed in the lid.

According to the present invention, since the rotation of the displacer is prevented by the rotation prevention mechanism, a stable cooling process can be performed.

It is sectional drawing of the cryogenic refrigerator which is one Embodiment of this invention. It is a disassembled perspective view of the rotary valve provided in the cryogenic refrigerator which is one Embodiment of this invention. It is sectional drawing which expands and shows the displacer vicinity provided in the cryogenic refrigerator which is one Embodiment of this invention. FIG. 4 is a sectional view taken along line AA in FIG. 3. It is sectional drawing which expands and shows the displacer vicinity provided in the cryogenic refrigerator which is a modification of this invention. FIG. 6 is a cross-sectional view taken along line BB in FIG. It is sectional drawing which expands and shows the displacer vicinity provided in the cryogenic refrigerator which is a conventional example. FIG. 8 is a cross-sectional view taken along the line CC in FIG.

DESCRIPTION OF SYMBOLS 1 Gas compressor 2 Cold head 3A First stage displacer 3B

Second stage displacer

4A, 4B

Cool storage material

6, 7 Cooling stage 8 Valve body 9 Valve plate 10 Cylinder part 10A First stage cylinder 10B Second stage cylinder 11 First stage expansion chamber 12 Second stage expansion chamber 13 Upper chamber 14 Crank 15 Motor 16 Rotating bearing 22 Scotch yoke 30

Engagement pins

30a, 30b End portion 31 Pin collar 31a Through hole 32 Shaft hole 33 Through hole 34 Fixed Bolt 35

Screw hole

36A, 36B Engagement groove 37

Upper cup

40A, 40B Engagement bolt 41 Upper end recess 50 Sealing material

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

1 to 4 are diagrams for explaining a cryogenic refrigerator that is an embodiment of the present invention. In the present embodiment, a Gifford McMahon refrigerator (hereinafter referred to as a GM refrigerator) will be described as an example of the cryogenic refrigerator.

The GM refrigerator according to the present embodiment includes a gas compressor 1 and a cold head 2. The cold head 2 has a housing 23 and a cylinder part 10. The gas compressor 1 draws in refrigerant gas from the intake port 1a, compresses it, and discharges it as high-pressure refrigerant gas from the discharge port 1b. Further, helium gas is used as the refrigerant gas.

The cylinder portion 10 has a two-stage configuration of a first-stage cylinder 10A and a second-stage cylinder 10B, and the second-stage cylinder 10B is set to be thinner than the first-stage cylinder 10A. Further, a first stage displacer 3A can be reciprocated in the first stage cylinder 10A, and a second stage displacer 3B can be reciprocated in the axial direction of each

cylinder

10A, 10B inside the second stage cylinder 10B. Has been inserted.

The first stage displacer 3A and the second stage displacer 3B are connected to each other by a joint mechanism (not shown). The first stage displacer 3A is provided with a cool storage material 4A, and the second stage displacer 3B is filled with the cool storage material 4B. Further, gas flow paths L1 to L4 through which the refrigerant gas passes are formed in the

first stage displacers

3A and 3B.

The first stage expansion chamber 11 is formed at the end of the first stage cylinder 10A on the second stage cylinder 10B side, and the upper chamber 13 is formed at the other end. A second-stage expansion chamber 12 is formed at the end of the second-stage cylinder 10B opposite to the first-stage cylinder 10A side.

The upper chamber 13 and the first stage expansion chamber 11 are connected to each other via a gas flow path L1, a first stage cold storage material filling chamber filled with the cold storage material 4, and a gas flow path L2. The first-stage expansion chamber 11 and the second-stage expansion chamber 12 are connected via the gas flow path L3, the second-stage cold storage material filling chamber filled with the cold storage material 4B, and the gas flow path L4. ing.

The cooling stage 6 is disposed at a position substantially corresponding to the first stage expansion chamber 11 in the outer peripheral surface of the first stage cylinder 10A. A cooling stage 7 is disposed at a position substantially corresponding to the second stage expansion chamber 12 in the outer peripheral surface of the second stage cylinder 10B.

The sealing material 50 is disposed in the vicinity of the end on the upper chamber 13 side in the outer peripheral surface of the first stage displacer 3A. The sealing material 50 seals between the outer peripheral surface of the first stage displacer 3A and the inner peripheral surface of the cylinder 10A.

As described above, when the refrigerant gas blows out between the inner wall of the first stage cylinder 10A and the outer wall of the first stage displacer 3A, the cooling efficiency of the GM refrigerator is lowered. Therefore, a seal member 50 that is in sliding contact with the inner peripheral surface of the first stage cylinder 10A is provided on the outer surface of the first stage displacer 3A to suppress the occurrence of refrigerant gas blow-through.

The first stage displacer 3A is connected to an output shaft 22a of a scotch yoke 22 constituting a rotation / reciprocating motion conversion mechanism through a connection mechanism (which will be described in detail later). The scotch yoke 22 is supported by a pair of sliding

bearings

17a and 17b fixed to the housing 23 so as to be movable in the axial direction of the

first stage displacers

3A and 3B. In the sliding bearing 17b, the airtightness of the sliding portion is maintained, and the space in the housing 23 and the upper chamber 13 are airtightly defined.

The motor 15 is connected to the scotch yoke 22. The rotational movement of the motor 15 is converted into a reciprocating movement by the crank 14 and the scotch yoke 22. This reciprocating motion is transmitted to the first stage displacer 3A via the output shaft 22a and the coupling mechanism, whereby the first stage displacer 3A is in the first stage cylinder 10A and the second stage displacer 3B is in the first stage. Reciprocal movement is performed in the second-stage cylinder 10B. In the present embodiment, the motor 15 and the scotch yoke 22 (including the output shaft 22a) constitute the drive device described in the claims.

When each first-

stage displacer

3A, 3B moves upward (Z1 direction) in the figure, the volume of the upper chamber 13 decreases, and conversely, the volumes of the first-stage and second-

stage expansion chambers

11 and 12 Will increase. Conversely, when the

first stage displacers

3A and 3B move downward in the figure, the volume of the upper chamber 13 increases and the volumes of the first and second

stage expansion chambers

11 and 12 decrease. To do. As the volumes of the upper chamber 13 and the

expansion chambers

11 and 12 change, the refrigerant gas moves through the gas flow paths L1 to L4.

Further, when the refrigerant gas passes through the

regenerators

4A and 4B filled in the

first stage displacers

3A and 3B, heat exchange is performed between the refrigerant gas and the

regenerators

4A and 4B. Thereby, the

cool storage materials

4A and 4B are cooled by the refrigerant gas.

In the refrigerant gas flow path, a rotary valve RV is disposed between the intake port 1 a and the discharge port 1 b of the compressor 1 and the upper chamber 13. The rotary valve RV has a function of switching the flow path of the refrigerant gas. Specifically, the rotary valve RV has a first mode for guiding the refrigerant gas discharged from the discharge port 1b of the gas compressor 1 into the upper chamber 13, and the refrigerant gas in the upper chamber 13 of the gas compressor 1. Switching processing to the second mode leading to the intake port 1a is performed.

The rotary valve RV has a valve body 8 and a valve plate 9. The valve plate 9 is made of, for example, an aluminum alloy, and the valve body 8 is made of, for example, tetrafluoroethylene (for example, BEAREE FL3000 manufactured by NTN). The valve body 8 and the valve plate 9 have flat sliding surfaces, and the flat sliding surfaces are in surface contact with each other. A thin film made of a hard material such as diamond-like carbon (DLC) is preferably formed on at least one of both sliding surfaces in order to reduce friction and improve wear resistance.

The valve plate 9 is rotatably supported in the housing 23 by a rotary bearing 16. When the eccentric pin 14a of the crank 14 that drives the scotch yoke 22 revolves around the rotation axis, the valve plate 9 rotates. The valve body 8 is pressed against the valve plate 9 by a coil spring 20 and fixed by a pin 19 so as not to rotate.

The coil spring 20 is provided with pressing means for pressing the valve body 8 so that the valve body 8 does not move away from the valve plate 9 when the pressure on the exhaust side becomes larger than the pressure on the supply side. It is. The force that presses the valve body 8 against the valve plate 9 during operation is generated by the pressure difference between the supply side pressure and the exhaust side pressure of the refrigerant gas acting on the valve body 8.

FIG. 2 is an exploded perspective view of the rotary valve RV. The flat sliding surface 8a of the cylindrical valve body 8 and the flat sliding surface 9a of the valve plate 9 are in surface contact. A gas flow path 8 b serving as a gas supply path passes through the valve body 8 along the central axis of the valve body 8. That is, one end of the gas flow path 8b is open to the sliding surface 8a.

The other end of the gas flow path 8b is connected to the discharge port 1b of the gas compressor 1 shown in FIG. From the discharge port 1b of the compressor 1 to the gas flow path 8b of the valve body 8 corresponds to a gas supply path.

A groove 8c is formed on the sliding surface 8a of the valve body 8 along an arc centered on the central axis of the valve body 8. One end of the gas flow path 8d formed inside the valve body 8 is open to the bottom surface of the groove 8c. The other end of the gas flow path 8d opens to the outer peripheral surface of the valve body 8, and further communicates with the upper chamber 13 via a gas flow path 21 formed in the housing 23 shown in FIG.

A groove 9d extending in the radial direction from the center is formed on the sliding surface 9a of the valve plate 9. When the valve plate 9 rotates and the outer peripheral end of the groove 9d partially overlaps the groove 8c, the gas flow path 8b and the gas flow path 8d communicate with each other through the groove 9d.

A gas flow path 9 b parallel to the rotation axis extends through the valve plate 9. The gas flow path 9b opens at substantially the same position as the groove 8c formed in the sliding surface 8a of the valve body 8 with respect to the radial direction in the sliding surface 9a. When the valve plate 9 rotates and the opening of the gas flow path 9b partially overlaps the groove 8c, the gas flow path 8d and the gas flow path 9b communicate with each other. The other end of the gas flow path 9b communicates with the intake port 1a of the gas compressor 1 through the cavity in the housing 23 shown in FIG. From the gas flow path of the valve plate 9 to the intake port 1a of the compressor 1 corresponds to the gas discharge path.

When the gas flow path 8b and the gas flow path 8d communicate with each other via the groove 8c, the refrigerant gas sent from the compressor 1 is sent into the upper chamber 13 via the rotary valve RV. When the gas flow path 8d and the gas flow path 9b are in communication, the refrigerant gas in the upper chamber 13 is recovered by the gas compressor 1. Therefore, when the valve plate 9 is rotated, introduction of refrigerant gas into the upper chamber 13 (supply) and recovery of refrigerant gas from the upper chamber 13 (exhaust) are repeated.

Next, in the GM refrigerator configured as described above, a connecting mechanism that connects the output shaft 22a, which is a reciprocating member of the scotch yoke 22, and the first stage displacer 3A will be described mainly with reference to FIGS. . FIG. 3 is an enlarged view showing a connecting portion between the output shaft 22a and the first stage displacer 3A, and FIG. 4 shows a cross section taken along line AA in FIG.

The connecting mechanism for connecting the output shaft 22a and the first stage displacer 3A (hereinafter simply referred to as the “displacer 3A”) is roughly composed of the output shaft 22a, the engaging pin 30, the pin collar 31, the shaft hole 32, the upper cup 37, and the like. It is comprised by the rotation prevention mechanism etc. The rotation prevention mechanism according to the present embodiment is configured to have

engagement grooves

36A and 36B.

The output shaft 22a extends in the vicinity of its lower end in a direction (indicated by arrows X1 and X2 in FIGS. 1 and 3) perpendicular to the reciprocating direction of the displacer 3A (indicated by arrows Z1 and Z2 in FIGS. 1 and 3). A through hole 33 is formed so as to achieve this. The engagement pin 30 is attached so as to penetrate the through hole 33. Therefore, in this attached state, the engaging pin 30 extends in the direction (X1, X2 direction) perpendicular to the reciprocating direction of the displacer 3A. Further, since the length of the engagement pin 30 is longer than the diameter of the output shaft 22a, both

end portions

30a and 30b of the engagement pin 30 are extended outward with the output shaft 22a as a center.

A pin collar 31 is provided at the lower end of the output shaft 22a. The pin collar 31 has a hollow cylindrical shape in which an insertion hole 31a into which the output shaft 22a is inserted is formed at the center. The pin collar 31 is made of, for example, stainless steel. Further, the pin collar 31 is formed with an insertion hole 31a extending in a direction perpendicular to the reciprocating direction of the displacer 3A.

In a state where the pin collar 31 is mounted at a predetermined mounting position of the output shaft 22a, the through hole 33 formed in the output shaft 22a and the insertion hole 31a formed in the pin collar 31 are in a state of communicating in a straight line. In this communication state, the engagement pin 30 is attached to the insertion hole 31 a and the through hole 33. The length of the engagement pin 30 is set longer than the diameter of the pin collar 31. Therefore, even when the engagement pin 30 is mounted on the output shaft 22a and the pin collar 31, both

end portions

30a and 30b of the engagement pin 30 extend outward from the outer peripheral surface with the pin collar 31 as the center. .

Further, in a state where the engagement pin 30 is mounted on the output shaft 22a and the pin collar 31, the pin collar 31 is held on the output shaft 22a via the engagement pin 30. Therefore, when the output shaft 22a moves in the reciprocating direction (Z1, Z2 direction) of the displacer 3A, the pin collar 31 also moves integrally in the reciprocating direction (Z1, Z2 direction).

The shaft hole 32 and the

engagement grooves

36A and 36B are formed at the upper end (the end in the Z1 direction) of the displacer 3A. The shaft hole 32 is formed coaxially with the central axis of the displacer 3A having a cylindrical shape. The diameter of the shaft hole 32 is set to be slightly larger than the diameter of the pin collar 31. That is, the shaft hole 32 is configured such that the output shaft 22a having the pin collar 31 attached therein can be inserted therein. The length of the engagement pin 30 is set longer than the diameter of the shaft hole 32.

The engaging grooves 36 A and 36 B are formed on the side wall of the shaft hole 32. The

engagement grooves

36A and 36B are formed 180 degrees apart from each other, and thus the engagement groove 36A and the engagement groove 36B are formed to face each other. The engaging

grooves

36A and 36B have the same shape, and therefore the length (indicated by an arrow L1 in FIG. 4) and the width (indicated by an arrow W in FIG. 4) have the same dimensions.

Further, the length L1 of each

engagement groove

36A, 36B is longer than the length (indicated by arrow L2 in FIG. 4) in which each

end

30a, 30b of the engagement pin 30 protrudes outward from the outer peripheral surface of the pin collar 31. (L1> L2). Further, the width W of each

engagement groove

36A, 36B is set to be larger than the cross-sectional diameter of the engagement pin 30 (indicated by arrow R in FIG. 4) (W> R). Therefore, by inserting and mounting the output shaft 22a to which the engagement pin 30 and the pin collar 31 are attached into the shaft hole 32, both

end portions

30a and 30b of the engagement pin 30 are inserted into the

engagement grooves

36A and 36B. A combined state is obtained (see FIG. 4).

The upper cup 37 functions as a lid that closes the upper end of the displacer 3A. The upper cup 37 is made of aluminum and has a disk shape with an insertion hole 37a formed in the center. The output shaft 22a is inserted through the insertion hole 37a. Further, the upper cup 37 is formed with a hole for forming the gas flow path L1 and a mounting recess for mounting the fixing bolt 34.

The upper cup 37 is fixed to the displacer 3A by inserting the fixing bolt 34 into the mounting recess and screwing into the screw hole 35 formed in the upper end portion of the displacer 3A. In this fixed state, the pin collar 31 is located below the upper cup 37. Further, the diameter of the insertion hole 37 a formed in the upper cup 37 is set smaller than the diameter of the pin collar 31. Therefore, the pin collar 31 is engaged (contacted) with the upper cup 37 while the upper cup 37 is fixed to the displacer 3A.

In the above configuration, when the output shaft 22a is moved upward (moved in the Z1 direction) by driving the drive device, the pin collar 31 attached to the output shaft 22a is also moved upward by the engagement pin 30. At this time, since the pin collar 31 is engaged with the upper cup 37, the upper cup 37 is also urged upward as the pin collar 31 moves upward.

Therefore, as the output shaft 22a moves upward, the pin collar 31 engages with the upper cup 37 and urges the displacer 3A to move upward. That is, the upper cup 37 is engaged with the output shaft 22a via the pin collar 31. Accordingly, the displacer 3A moves upward as the output shaft 22a moves upward.

Also, when the output shaft 22a moves down, the displacer 3A moves down as the output shaft 22a moves down for the same reason as described above. Therefore, according to the connection mechanism according to the present embodiment, the displacer 3A can be reciprocated in the vertical direction by the vertical movement of the output shaft 22a of the drive device.

Here, it is assumed that force is applied to the displacer 3A in the rotational direction (indicated by arrows C1 and C2 in FIG. 4) in the coupling mechanism according to the present embodiment.

Now, assuming that a force for rotating the displacer 3A in the direction indicated by the arrow C1 in FIG. 4 is applied, the engaging

grooves

36A and 36B also rotate in the direction of the arrow C1 as the displacer 3A rotates in the C1 direction. Therefore, with the rotation in the C1 direction, one inner wall of the engagement groove 36A engages (contacts) with the end 30a of the engagement pin 30 and one inner wall of the engagement groove 36B ends with the end of the engagement pin 30. It will be in the state engaged with the part 30b.

However, since the output shaft 22a is connected to the scotch yoke mechanism that constitutes the drive device as described above, the output shaft 22a is not rotatable, and therefore the engagement pin 30 penetrated through the through hole 33 of the output shaft 22a is also included. It cannot be rotated. Therefore, after the inner walls of the

engagement grooves

36A and 36B are engaged with the

end portions

30a and 30b of the engagement pin 30, further rotation of the displacer 3A in the C1 direction is restricted.

The same applies when a force for rotating the displacer 3A in the direction indicated by the arrow C2 in FIG. 4 is applied to the displacer 3A, and the other inner wall of the engaging groove 36A is the end of the engaging pin 30 along with the rotation in the C2 direction. The other inner wall of the engagement groove 36 B engages with the end 30 b of the engagement pin 30. Therefore, after the inner walls of the

engagement grooves

36A and 36B are engaged with the

end portions

30a and 30b of the engagement pin 30, further rotation of the displacer 3A in the C2 direction is also restricted.

In this embodiment, the restriction of the rotation of the displacer 3A is performed by engaging both

end portions

30a and 30b of the engagement pin 30 with a pair of

engagement grooves

36A and 36B constituting the rotation prevention mechanism. That is, the rotation of the displacer 103 is conventionally restricted only by the spring pin 107, in other words, only at one place, whereas in this embodiment, the rotation of the displacer 3A can be restricted at two places.

Therefore, since the shearing force applied to the

end portions

30a and 30b of the engagement pin 30 when the rotation of the displacer 3A is restricted can be made smaller than before, the engagement pin 30 is damaged when the rotation of the displacer 3A is restricted. Can be prevented. This prevents the sealing material 50 disposed in the displacer 3A from separating from the first-stage cylinder 10A and prevents the refrigerant gas from being blown out, thereby stabilizing the cooling process of the GM refrigerator. .

In this embodiment, a solid round bar made of metal (for example, stainless steel) is used as the engagement pin 30. Therefore, the strength of the engagement pin 30 is stronger than that of the conventional spring pin 107, and this also prevents damage to the engagement pin 30.

Further, in the present embodiment, the conventionally required spring pin 107 can be omitted, and the formation of a fixing hole for fixing the spring pin 107 to the upper cup 105 is also unnecessary.

Furthermore, in this embodiment, it is not necessary to form the groove 102a in the pin collar 102 which is a small part with respect to the displacer 103. Therefore, according to the GM refrigerator according to the present embodiment, it is possible to reduce the number of parts and simplify the manufacturing process as compared with the refrigerator having the conventional configuration.

5 and 6 show a modification of the above-described coupling mechanism. In the connection mechanism according to the above-described embodiment, the

engagement grooves

36A and 36B are provided as the rotation preventing mechanism, and when the first stage displacer 3A rotates in the C1 and C2 directions, the engagement pin 30 and the

engagement grooves

36A and 36B are provided. Are engaged (contacted) to prevent the first-stage displacer 3A from rotating.

On the other hand, this modification is characterized in that a standing pin standing on the upper end of the first stage displacer 3A is used as a rotation preventing mechanism of the coupling mechanism. In this modification,

bolts

40A and 40B (hereinafter referred to as

engagement bolts

40A and 40B) are used as the standing pins.

Two engagement bolts 40A are arranged at one end 30a of the engagement pin 30, and two engagement bolts 40B are arranged at the other end 30b of the engagement pin 30. Therefore, in this modification, a total of four

bolts

40A, 40B are erected on the upper end of the first stage displacer 3A.

It should be noted that the standing pins are not limited to bolts, and it is possible to use other components as long as they can stand upright at the upper end of the first stage displacer 3A.

On the other hand, a circular recess 41 (hereinafter referred to as an upper end recess 41) is formed at the upper end of the first stage displacer 3A. The output shaft 22 a is inserted through the center position of the upper end recess 41. The diameter of the upper end recess 41 is set to be longer than the length of the engagement pin 30.

Further, four screw holes are formed in the bottom surface of the upper end recess 41. When the four

bolts

40A and 40B are screwed into the screw holes, the four

bolts

40A and 40B are erected on the first stage displacer 3A (specifically, the bottom surface of the upper end recess 41).

As shown in FIG. 6, the pair of engagement bolts 40 A is erected at a position sandwiching the end 30 a of the engagement pin 30 when the output shaft 22 a is attached to the first stage displacer 3 A. Similarly, the pair of engagement bolts 40B is erected at a position sandwiching the end 30b of the engagement pin 30 when the output shaft 22a is attached to the first stage displacer 3A.

On the other hand, engaging

recesses

42A and 42B are formed at positions corresponding to the positions where the engaging

bolts

40A and 40B of the upper cup 37 are disposed. The engaging

recesses

42A and 42B are configured to engage with the upper ends of the engaging

bolts

40A and 40B provided upright on the pin collar 31 when the upper cup 37 is mounted on the first stage displacer 3A. (See FIG. 5).

As described above, the lower ends of the

respective engagement bolts

40A and 40B are bolted to the first stage displacer 3A and the upper ends thereof are fixed by engaging with the engagement recesses 42A and 42B of the upper cup 37. The As described above, the engaging

bolts

40A and 40B have high strength because their upper and lower ends are fixed.

In the coupling mechanism according to this modification having the above-described configuration, it is assumed that a force is applied to the displacer 3A in the rotation direction (indicated by arrows C1 and C2 in FIG. 6).

Now, assuming that a force for rotating the displacer 3A in the direction indicated by the arrow C1 in FIG. 4 is applied, the

engagement bolts

40A and 40B also rotate in the arrow C1 direction as the displacer 3A rotates in the C1 direction. . Therefore, with this rotation in the C1 direction, one engagement bolt 40A (the engagement bolt 40A positioned below in FIG. 6) of the pair of engagement bolts 40A is engaged with the end 30a of the engagement pin 30. (Contact). Similarly, one engagement bolt 40B (the engagement bolt 40A positioned on the upper side in FIG. 6) of the pair of engagement bolts 40B is engaged (contacted) with the end portion 30b.

As described above, since the output shaft 22a is connected to the scotch yoke mechanism that constitutes the drive device, the output shaft 22a cannot rotate, and the engagement pin 30 also cannot rotate. Therefore, after the

engagement bolts

40A and 40B are engaged with the

end portions

30a and 30b of the engagement pin 30 as described above, the displacer 3A is restricted from further rotation in the C1 direction.

The same applies when a force for rotating the displacer 3A in the direction indicated by the arrow C2 in FIG. 6 is applied, and the engagement bolt 40A is different from that engaged with the

end portions

30a and 30b when rotated in the C1 direction. , 40B are engaged (contacted) with the

end portions

30a, 30b, thereby restricting the rotation of the displacer 3A in the C2 direction.

As described above, in this modification, the restriction of the rotation of the displacer 3A is performed by engaging both

end portions

30a and 30b of the engagement pin 30 with the

engagement bolts

40A and 40B constituting the rotation prevention mechanism.

At this time, the engaging

bolts

40A and 40B are firmly fixed to the first stage displacer 3A and the upper cup 37 at the upper and lower sides as described above, and therefore the first stage displacer 3A is rotated. It can be surely prevented. Moreover, when each

engagement bolt

40A, 40B is a firm structure, when engaging with the engagement pin 30, it can prevent that

engagement bolt

40A, 40B is damaged.

Here, in this modification, the

engagement bolts

40A and 40B are used as the standing pins and are fixed by being screwed into the screw holes formed in the bottom surface of the upper end recess 41. It is good also as a structure fixed to the bottom face of the upper end recessed part 41 using an adhesive agent.

In the present modification, the four

engagement bolts

40A, 40A, 40B, and 40B are engaged with the engagement pin 30. However, two engagement bolts are provided only on one end of the engagement pin 30. It is good also as a structure which a joint bolt engages.

Specifically, only one of the two

engagement bolts

40A and 40A may be provided on one end 30a of the engagement pin 30, and two

engagement bolts

40A and 40A may be provided on the other end 30a of the engagement pin 30. It is good also as a structure which provides only volt | bolt 40B and 40B.

Further, one

engagement bolt

40A, 40B is disposed at each of both

end portions

30a, 30b of the engagement pin 30, and the pair of

engagement bolts

40A, 40B are disposed on the same side of the engagement pin 30 together. It is good also as a structure.

Specifically, in FIG. 6, only the

engagement bolts

40A and 40B located on the upper side of the engagement pin 30 in the drawing may be left, and the

engagement bolts

40A and 40B located on the lower side may be removed. Conversely, in FIG. 6, only the engagement bolts 40 A and 40 B positioned on the lower side of the engagement pin 30 in the drawing may be left, and the engagement bolts 40 A and 40 B positioned on the upper side may be removed.

The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific embodiments described above, and various modifications are possible within the scope of the gist of the present invention described in the claims. It can be modified and changed.

Specifically, the present invention is not limited to the two-stage type, but can be applied to a single-stage or multi-stage GM refrigerator. Further, the present invention is not limited to the one that generates reciprocating motion by the Scotch yoke mechanism, and can be applied to other mechanisms that generate reciprocating motion, such as a crank mechanism.

Although it is conceivable that the displacer 3A is completely fixed to the output shaft 22a, the displacer 3A is configured to reciprocate in the cylinder portion 10, and thus allows rotation to some extent within a range in which refrigerant gas does not blow through. It is desirable. In this embodiment, by adjusting the width W of the

engagement grooves

36A and 36B with respect to the diameter R of the engagement pin 30, this allowable rotation range can be easily set.

This international application claims priority based on Japanese Patent Application No. 2010-093281 filed on April 14, 2010. The entire contents of Japanese Patent Application No. 2010-093281 are incorporated herein by reference. Incorporate.

Claims

A cylinder to which refrigerant gas is supplied;
A displacer that reciprocates in the cylinder;
A drive device for reciprocating the displacer in the cylinder;
A cryogenic refrigerator having a connecting mechanism for connecting the driving device and the displacer,
The coupling mechanism is
An output shaft extending from the drive device to the displacer;
An engagement pin provided through the output shaft so as to extend in a direction intersecting the reciprocating direction of the displacer;
An anti-rotation mechanism that engages with the engagement pin when the displacer rotates and prevents the displacer from rotating;
A cryogenic refrigerator having a lid fixed to the one end of the displacer and engaged with the output shaft.
The rotation prevention mechanism is
2. The cryogenic refrigerator according to claim 1, further comprising an engaging groove formed on the displacer and engaged with an end of the engaging pin when the output shaft is mounted on the displacer. .
The rotation prevention mechanism is
2. The cryogenic refrigeration according to claim 1, further comprising a standing pin that is erected on the displacer and that engages with an end of the engaging pin when the output shaft is mounted on the displacer. Machine.
The cryogenic refrigerator according to claim 1, wherein the engagement pin is a solid round bar.
The upright pin is a bolt, and a screw part formed in a lower part is screwed into the displacer, and an upper part engages with a concave part formed in the lid. 3. The cryogenic refrigerator according to 3.